Operant down-conditioning of the soleus H-reﬂex in people after stroke

Frontiers in Rehabilitation Sciences, 2022 · DOI: 10.3389/fresc.2022.859724 · Published: July 22, 2022

Neurology Neuroplasticity Rehabilitation

Simple Explanation

This study investigates whether people who have had a stroke can learn to control their spinal reflexes using a technique called operant down-conditioning. This technique uses visual feedback to help individuals reduce the size of their soleus H-reflex, a measure of spinal cord excitability. The study involved 12 individuals with chronic stroke who participated in multiple sessions where they received feedback while trying to decrease their H-reflex size. The researchers found that about half of the participants were successful in reducing their reflex size. Those who successfully reduced their H-reflex also showed improvements in their walking speed. This suggests that this type of reflex training may be a useful tool for improving motor function after stroke.

Study Duration

12 weeks

Participants

12 stroke people with chronic spastic hemiparesis

Evidence Level

Original Research

Key Findings

1
Operant down-conditioning can decrease the soleus H-reﬂex size in some people after stroke, specifically in 50% of the participants in this study.
2
Participants who successfully decreased their H-reﬂex size also showed an increase in their 10-meter walking speed.
3
The time course of H-reﬂex changes differed between stroke patients and individuals with spinal cord injury, suggesting that the location of the injury affects the reflex conditioning-induced plasticity.

Research Summary

This study examined the feasibility of operant down-conditioning of the soleus H-reflex in individuals after stroke with chronic spastic hemiparesis. Twelve participants completed 6 baseline and 30 conditioning sessions over 12 weeks. The results showed that in six of the twelve participants, the conditioned H-reflex became significantly smaller by 30% on average. These participants also experienced an increase in ten-meter walking speed. The findings suggest that reflex down-conditioning is feasible in people after stroke and may have potential therapeutic benefits for improving gait function. However, the success rate and time course of reflex changes differ from those observed in individuals with spinal cord injury.

Practical Implications

Therapeutic Potential

H-reﬂex down-conditioning may be a valuable therapeutic intervention for improving walking speed and motor function in individuals post-stroke.

Personalized Rehabilitation

The study underscores the need for personalized rehabilitation approaches, as conditioning success varied among participants, highlighting the influence of lesion location and individual neural mechanisms.

Further Research

Additional research is necessary to fully understand the clinical and functional impact of H-reﬂex down-conditioning and to identify factors that predict conditioning success in stroke survivors.

Study Limitations

1
The sample size of 12 participants is relatively small.
2
Lack of data on the volume of preserved sensorimotor cortex or corticospinal tract.
3
The study did not assess clinical spasticity after conditioning.

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